산소결핍 페롭스카이트 La⅓Sr⅔FeO2.96의 외부 자기장 하에서의 Mossbauer 분광학적 연구

다국어 초록 (Multilingual Abstract)

The origin for the charge disproportionation (CD) transition in polycrystalline La(⅓)Sr(⅔)FeO(2.96) was examined using X-ray diffraction and the external field Mossbauer spectroscopy. In order to see how the external magnetic field affects the CD state above its transition temperature, an external magnetic field of up to 6 T was applied either parallel or perpendicular to the γ-ray direction with the sample temperature fixed at 225 K, which was above the CD transition temperature. Without an external magnetic field, a completely paramagnetic singlet was obtained in the temperature range of the averaged valence state above the transition temperature, which was interpreted as coming from the average valence Fe^(3.6+). In the longitudinal geometry, a magnetic Zeeman with its intensity ratio 3:0:1:1:0:3 is superimposed to the central singlet. In the transverse geometry, however, the central singlet disappears and only a magnetic component with its intensity ratio 3:4:1:1:4:3 emerges. The existence of a singlet is understood as an evidence of the fast electron-transfer among Fe ions. Since the singlet still exists under the magnetic field, the application of an external field has little effect on the conduction mechanism of hopping electrons.